Capacitive single layer multi-touch panel having improved response characteristics

ABSTRACT

An apparatus is provided. A substrate and a cover plate are provided. A sensor layer is formed on at least one of the substrate and the cover plate. The sensor layer includes a plurality of row electrodes and a plurality of column electrodes interleaved with the plurality of row electrodes, where each row electrode and each column electrode is formed of a plurality of stair-stepped diamonds. An insulator is also included so as to electrically isolate the plurality of row electrodes and the plurality of column electrodes, where the insulator is substantially transparent to visible spectrum light. The apparatus employs mirror symmetric row sensor routing placement. The routing placement provides reduction of row bonding pads by 50% to enhance manufacturing yield. Rearranging unit cells on the same layout results in a decrease of RC parasitics by 50%.

This application is a continuation of prior application Ser. No.13/872,448, filed Apr. 29, 2013, currently pending, which is acontinuation of PCT/CN2013/071011, filed Jan. 28, 2013, the entiretiesof which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates generally to a touch panel and, more particularly,to a capacitive touch panel having an improved response.

BACKGROUND

Turning to FIGS. 1 and 2, an example of a conventional system 100 can beseen. System 100 generally comprises a touch panel 102 and touch panelcontroller 104. The touch panel 102 has an array of sensors formed by aset of column electrodes (e.g., electrode 103), where each electrode ofeach column is coupled together by a strip electrode (e.g., stripelectrode 107), and a set of row electrodes (e.g., electrode 105), whereeach electrode of each row is coupled together by a strip electrode(e.g., strip electrode 109). Usually, the column and row electrodes(e.g., electrodes 103 and 105) are formed in two separate layers with adielectric or insulating layer formed therebetween, and these conductivelayers which form the electrodes (e.g., electrodes 105 and 109) aregenerally transparent to visible spectrum light (e.g., light having awavelength from about 380 nm to about 750 nm). The strip electrodes foreach column (e.g., strip electrode 107) are then coupled to theinterface or I/F 106 of the touch panel controller 104 by terminals X-1to X-N, while the strip electrodes for each row (e.g., strip electrode109) are coupled to the interface 106 by terminals Y-1 to Y-M. Theinterface 106 is able to communicate with the control circuit 108. Asshown in greater detail in FIG. 2, the interface 106 is generallycomprised of a multiplexer or mux 202 and an exciter 204.

In operation, the interface 106 (which is usually controlled by thecontrol circuit 108) selects and excites columns of electrodes (e.g.,electrode 103) and “scans through” the rows of row electrodes (e.g.,electrode 105) so that a touch position from a touch event can beresolved. As an example, interface 204 can excite two adjacent columnsthrough terminals X-j and X-(j+1) with excitation signals EXCITE[j] andEXCITE[j+1], and interface 106 receives a measurement signal from a rowassociated with terminal Y-i. When an object (e.g., finger) is inproximity to the touch panel (which is generally considered to be atouch event), there is a change in capacitance due at least in part tothe arrangement of electrodes (e.g., electrodes 103 and 105), and thecontroller 108 is able to resolve the position of the touch event.

Most conventional touch panels (e.g., touch panel 102) do, however,exhibit a non-uniform response characteristic, which is manifested asnon-uniform signal strength across the panel. This non-uniformity isgenerally caused by natural variations in the patterns forming thecolumn and row electrodes (e.g., electrodes 103 and 105). In otherwords, the electrodes are arranged to have gaps or non-overlappingregions between the electrodes so that, as an object (e.g., finger)traverses the panel (e.g., panel 102) and passes over thesenon-overlapping regions, the signal strength or measured capacitancechanges. Therefore, there is a need for a touch panel having a moreuniform response characteristic.

Some examples of other conventional systems are: U.S. Pat. Nos.4,237,421; 6,188,391; U.S. Pat. No. 7,714,847; U.S.; U.S. Pat. No.8,278,571; Patent Pre-Grant Publ. No. 2006/0097991; U.S. PatentPre-Grant Publ. No. 2009/0091551; U.S. Patent Pre-Grant Publ. No.2010/0149108; U.S. Patent Pre-Grant Publ. No. 2010/0156810; U.S. PatentPre-Grant Publ. No. 2010/0321326; U.S. Patent Pre-Grant Publ. No.2011/0095996; U.S. Patent Pre-Grant Publ. No. 2011/0095997; U.S. PatentPre-Grant Publ. No. 2011/0102361; U.S. Patent Pre-Grant Publ. No.2011/0157079; U.S. Patent Pre-Grant Publ. No. 2012/0056664; PCT Publ.No. WO2009046363; and PCT Publ. No. WO2011018594.

SUMMARY

An embodiment of the present invention, accordingly, provides anapparatus comprising:

a substrate; a cover plate that is substantially transparent to visiblespectrum light; a sensor layer formed on at least one of the substratesand the cover plate, wherein the sensor layer includes: a plurality ofrow electrodes; a plurality of column electrodes interleaved with theplurality of row electrodes, wherein the intersections of each rowelectrode and each column electrode are arrayed in a logical arraydefined to reduce parasitic capacitance and resistance; traces formed inthe single layer electrically connected to each of the row and columnelectrodes; and a board configured for attaching to the substrate, theboard including vias and routing that provide an equivalent ofelectrical crossovers to electrically connect each of the electrodes ina row to one another while providing electrical isolation from rowelectrodes and traces associate with other rows.

In accordance with the present invention, the conductive layer is formedon the cover plate.

In accordance with the present invention, the conductive layer is formedon the substrate.

In accordance with the present invention, the first and second columnsof electrodes are horizontal mirror images of one another, the third andforth columns of electrodes are horizontal mirror images of one anotherand continuing on with columns n-1 and n being horizontal images of oneanother to complete the column layout in the array.

In accordance with the present invention, the intersections of each rowelectrode of the row of electrodes with the first and second columns ofelectrodes is a vertical mirror image of the row of electrodes thatintersect with third and fourth columns of electrodes and continuing onwith alternating rows with alternating mirrored pairs of columns ofelectrodes.

In accordance with the present invention, each of the interleaved pairsof columns and rows is formed of a single conductive trace.

In accordance with the present invention, the single conductive trace issubstantially transparent to visible spectrum light.

In accordance with the present invention, an insulator that electricallyisolates the plurality of row electrodes and the plurality of columnelectrodes is substantially transparent to visible spectrum light.

An embodiment of the present invention, accordingly, provides anapparatus comprising: a touch panel having: a substrate; a cover platethat is substantially transparent to visible spectrum light; a sensorlayer formed on at least one of the substrates and the cover plate,wherein the sensor layer includes: a plurality of row electrodes; aplurality of column electrodes interleaved with the plurality of rowelectrodes, wherein the intersections of each row electrode and eachcolumn electrode are arrayed in a logical array defined to reduceparasitic capacitance and resistance; and an insulator that electricallyisolates the plurality of row electrodes and the plurality of columnelectrodes, wherein the insulator is substantially transparent tovisible spectrum light; traces formed in the single layer electricallyconnected to each of the row and column electrodes; a board configuredfor attaching to the substrate, the board including vias and routingthat provide an equivalent of electrical crossovers to electricallyconnect each of the electrodes in a row to one another while providingelectrical isolation from row electrodes and traces associate with otherrows; an interconnect that is coupled to each row electrode and eachcolumn electrode; and a touch panel controller that is coupled to theinterconnect.

In accordance with the present invention, the conductive layer is formedon the cover plate.

In accordance with the present invention, the conductive layer is formedon the substrate.

In accordance with the present invention, the first and second columnsof electrodes are horizontal mirror images of one another, the third andforth columns of electrodes are horizontal mirror images of one anotherand continuing on with columns n-1 and n being horizontal images of oneanother to complete the column layout in the array.

In accordance with the present invention, the intersections of each rowelectrode of the row of electrodes with the first and second columns ofelectrodes is a vertical mirror image of the row of electrodes thatintersect with third and fourth columns of electrodes and continuing onwith alternating rows with alternating mirrored pairs of columns ofelectrodes.

In accordance with the present invention, each of the interleaved pairsof columns and rows is formed of a single conductive trace.

In accordance with the present invention, the single conductive trace issubstantially transparent to visible spectrum light.

In accordance with the present invention, an insulator that electricallyisolates the plurality of row electrodes and the plurality of columnelectrodes is substantially transparent to visible spectrum light.

In accordance with the present invention, the touch panel is coupled tothe board.

An embodiment of the present invention, accordingly, provides anapparatus comprising: a touch panel having: a display; a substrate thatis secured to the display, wherein the substrate is substantiallytransparent to visible spectrum light; a sensor layer formed over thesubstrate, wherein the sensor layer includes: a plurality of rowelectrodes formed over the substrate; a plurality of column electrodesformed over the substrate, wherein each column electrode is interleavedwith the plurality of row electrodes, wherein the intersections of eachrow electrode and each column electrode are arrayed in a logical arraydefined to reduce parasitic capacitance and resistance; and a firstinsulator that is formed over the substrate and the sensor layer,wherein the first insulator is substantially transparent to visiblespectrum light, and wherein the first insulator electrically isolatesthe plurality of row electrodes and the plurality of column electrodes;a cover plate that is secured to the first insulator layer, wherein thecover plate is substantially transparent to visible spectrum light; aninterconnect that is coupled to each column electrode and each rowelectrode; and a touch panel controller having: an interface that iscoupled to the interconnect; and a control circuit that is coupled tothe interface.

In accordance with the present invention, each the plurality of rowelectrodes and column electrodes is formed of a conductive trace.

In accordance with the present invention, the plurality of rowelectrodes, the plurality of column electrodes, and the plurality ofbridge conductors are formed of indium tin oxide (ITO).

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 are diagrams of an example of a conventional system;

FIG. 3 is diagrams of an example of a system in accordance with thepresent invention;

FIG. 4 is an example of a conventional single layer portion of a touchpanel of FIG. 3;

FIG. 5 is an example of layout of optimized to reduce the number of rowbonding pads;

FIG. 6 is a physical layout of a portion of a touch panel in accordancewith the present invention; and

FIG. 7 depicts an example an actual layout of a 6 row by 4 columntouchpad.

DETAILED DESCRIPTION

Refer now to the drawings wherein depicted elements are, for the sake ofclarity, not necessarily shown to scale and wherein like or similarelements are designated by the same reference numeral through theseveral views.

Turning to FIG. 3, an example of a system 200 in accordance with thepresent invention can be seen. System 200 is similar in construction tosystem 100 except that touch panel 102 has been replaced by touch panel202. Additionally, interconnect 204 has been provided to providecommunication channels between the touch panel controller 104 and thetouch panel 202.

In FIG. 4, a 4 row by 2 column portion of conventional single layertouch panel can be seen. As shown in this example, the touch panel isgenerally comprised of a touch sensor disposed over or positioned over adisplay (which can, for example be a liquid crystal display or LCD) soas to allow the light from the display to project through the sensor.This means that each trace of the layer sensor is substantiallytransparent to visible spectrum light. As shown, the touch sensor is asingle layer sensor, having rows R1, R2, R3 and R4 and columns C1 andC2. The column and row traces, in this example, each have a conductivelayer disposed on a substrate. Typically, the substrate is formed ofglass (which is substantially transparent to visible spectrum light),and the conductive layer is usually formed of a conductive material thatis generally transparent to visible spectrum light (such as indium tinoxide, aluminum doped zinc oxide, gallium doped zinc oxide, or indiumdoped zinc oxide). The conductive layer is usually formed by electronbeam evaporation, physical vapor deposition (PVD), or sputter depositionon the substrate, which can, for example, then be patterned using laserablation or etching so to form the detection electrodes. The sensorlayers can then be secured to the cover plate, using an insulating ordielectric material (which can be an adhesive, like epoxy).

In order to achieve a more uniform response characteristic for the touchsensor, the patterns for the conductors should be modified. As shown inthe example of FIGS. 5 and 6, row and column traces are interleavedacross the touch sensor. The interleaving can vary in configurationbased on the logical arrangement of the conductors but are intended toreduce the size, parasitic resistance and capacitance (and, thus, theimpact) of the array and produce a generally uniform responsecharacteristic across the touch sensor.

In FIGS. 6 and 7, examples of configurations for the row and columnlogical arrangements are shown. In FIG. 6, the far and end rows havebeen shuffled to reduce RC loading. The shuffling is de-shuffled indigital processing in the control circuit 108 of the touch panelcontroller 104. In this example, electrode of row R1 associated withcolumn C1 and column C2 has the longest routing trace which can be 30kilohms or higher. Parasitic fringing capacitance of row R1 resultedfrom coupling with its neighbor hood rows are also the largest of all.However, both R and C come down to minimum for logical row R1′associated with column C3 and column C4. Following the same arrangementrow R2 in column C1 and column C2 is shuffled from the high RC scenariodown to low RC scenario in column C3 and column C4. By placing thecolumns in a mirror symmetric manner as shown in FIG. 6, the bondingpads on the rows are reduced by 50%. FIG. 7 shows and exemplary layoutof a 6 row by 4 column touch pad as disclosed in this invention.

As a result of using the configurations shown in FIGS. 6 and 7, severaladvantages can be realized. One advantage is that the touch panel has amore uniform response characteristic because of the reduction inparasitic capacitance and resistance (the worst case RC is reduced by50%). Also, because the touch panel in the present invention is a truesingle metal configuration, where bonding failure is a majormanufacturing bottleneck, yield due to reduced bonding pad count isenhanced and thus processing cost is reduced.

Having thus described the present invention by reference to certain ofits preferred embodiments, it is noted that the embodiments disclosedare illustrative rather than limiting in nature and that a wide range ofvariations, modifications, changes, and substitutions are contemplatedin the foregoing disclosure and, in some instances, some features of thepresent invention may be employed without a corresponding use of theother features. Accordingly, it is appropriate that the appended claimsbe construed broadly and in a manner consistent with the scope of theinvention.

What is claimed is:
 1. An apparatus comprising: a touch panelcomprising: a sensor layer comprising: a first sensor in a first columnand a first physical row, the first sensor comprising: a first columnelectrode; and a first row electrode; a second sensor in a second columnand the first physical row, the second sensor comprising: a secondcolumn electrode; and a second row electrode coupled to the first rowelectrode; a third sensor in a third column and a second physical row,wherein the second physical row is different than the first physicalrow, the third sensor comprising: a third column electrode; and a thirdrow electrode; and a fourth sensor in a fourth column and the secondphysical row, the fourth sensor comprising: a fourth column electrode;and a fourth row electrode coupled to the third row electrode; a touchpanel controller comprising a control circuit; and interconnect couplingthe touch panel to the touch panel controller; and wherein the controlcircuit is configured to assign the first row electrode, the second rowelectrode, the third row electrode, and the fourth row electrode in afirst logical row.
 2. The apparatus of claim 1, wherein the first rowelectrode, the second row electrode, the third row electrode, and thefourth row electrode are in a first layer, wherein the first columnelectrode, the second column electrode, the third column electrode, andthe fourth column electrode are in a second layer, and wherein asubstantially transparent insulator is disposed between the first layerand the second layer.
 3. The apparatus of claim 1, wherein the touchpanel controller further comprises an interface (I/F) controlled by thecontrol circuit, the I/F comprising; an exciter configured to scanthrough the first physical row and the second physical row; and amultiplexer.
 4. The apparatus of claim 1, wherein the control circuit isconfigured to detect a finger in proximity to the touch panel.
 5. Theapparatus of claim 1, wherein the sensor layer is symmetric, wherein thefirst column is a mirror image of the fourth column and the secondcolumn is a mirror image of the third column.
 6. The apparatus of claim1, wherein the touch panel further comprises: a substantiallytransparent substrate; and a conductive layer disposed on thesubstantially transparent substrate.
 7. An apparatus comprising: a touchpanel comprising: a sensor layer comprising: a first sensor in a firstcolumn and a first physical row, the first sensor comprising: a firstcolumn electrode; and a first row electrode; a second sensor in a secondcolumn and the first physical row, the second sensor comprising: asecond column electrode; and a second row electrode coupled to the firstrow electrode; a third sensor in a third column and a second physicalrow, wherein the second physical row is different than the firstphysical row, the third sensor comprising: a third column electrode; anda third row electrode; and a fourth sensor in a fourth column and thesecond physical row, the fourth sensor comprising: a fourth columnelectrode; and a fourth row electrode coupled to the third rowelectrode; a touch panel controller comprising a control circuit,wherein the sensor layer comprises a plurality of traces in a singlelayer, the plurality of traces connected to the first row electrode, thesecond row electrode, the third row electrode, the fourth row electrode,the first column electrode, the second column electrode, the third rowelectrode, and the fourth row electrode; interconnect coupling the touchpanel to the touch panel controller, wherein the interconnect is coupledto the plurality of traces; and wherein the control circuit isconfigured to assign the first row electrode, the second row electrode,the third row electrode, and the fourth row electrode in a first logicalrow.
 8. The apparatus of claim 7, wherein the sensor layer is symmetric,wherein the first column is a mirror image of the fourth column, thesecond column is a mirror image of the third column, and the pluralityof traces is symmetric across a mirror plane.
 9. The apparatus of claim8, wherein the plurality of traces is interleaved across the touchpanel.
 10. The apparatus of claim 7, wherein the touch panel furthercomprises: a substantially transparent substrate; and a conductive layerdisposed on the substantially transparent substrate, wherein theconductive layer comprises the plurality of traces.
 11. The apparatus ofclaim 10, wherein the touch panel further comprises a cover platecoupled between the substantially transparent substrate and theconductive layer.
 12. The apparatus of claim 10, wherein the conductivelayer comprises indium tin oxide, aluminum doped zinc oxide, galliumdoped zinc oxide, or indium doped zinc oxide.
 13. The apparatus of claim10, wherein the touch panel further comprises a display coupled to thesubstantially transparent substrate.
 14. An apparatus comprising: atouch panel comprising: a sensor layer comprising: a first sensor in afirst column and a first physical row, the first sensor comprising: afirst column electrode; and a first row electrode; a second sensor in asecond column and the first physical row, the second sensor comprising:a second column electrode; and a second row electrode coupled to thefirst row electrode; a third sensor in a third column and a secondphysical row, wherein the second physical row is different than thefirst physical row, the third sensor comprising: a third columnelectrode; and a third row electrode; and a fourth sensor in a fourthcolumn and the second physical row, the fourth sensor comprising: afourth column electrode; and a fourth row electrode coupled to the thirdrow electrode; a fifth sensor in the first column and the secondphysical row, the fifth sensor comprising: a fifth column electrodecoupled to the first column electrode; and a fifth row electrode; asixth sensor in the second column and the second physical row, the sixthsensor comprising: a sixth column electrode coupled to the second columnelectrode; and a sixth row electrode coupled to the fifth row electrode;a seventh sensor in the third column and the first physical row, theseventh sensor comprising: a seventh column electrode coupled to thethird column electrode; and a seventh row electrode; and an eighthsensor in the fourth column and the first physical row, the eighthsensor comprising: an eighth column electrode coupled to the fourthcolumn electrode; and an eighth row electrode coupled to the seventh rowelectrode.
 15. The apparatus of claim 14, further comprising a controlcircuit configured to: assign the first row electrode, the second rowelectrode, the third row electrode, and the fourth row electrode in afirst logical row; and assign the fifth row electrode, the sixth rowelectrode, the seventh row electrode, and the eighth row electrode in asecond logical row, wherein the second logical row is different than thefirst logical row.
 16. The apparatus of claim 15, wherein the sensorlayer further comprises: a ninth sensor in the first column and a thirdphysical row, the ninth sensor comprising: a ninth column electrodecoupled to the first column electrode and the fifth column electrode;and a ninth row electrode; a tenth sensor in the second column and thethird physical row, the tenth sensor comprising: a tenth columnelectrode coupled to the second column electrode and the sixth columnelectrode; and a tenth row electrode coupled to the ninth row electrode;an eleventh sensor in the third column and a fourth physical row, theeleventh sensor comprising: an eleventh column electrode coupled to thethird column electrode and the third column electrode; and an eleventhrow electrode; and a twelfth sensor in the fourth column and the fourthphysical row, the twelfth sensor comprising: a twelfth column electrodecoupled to the eight column electrode and the fourth column electrode;and a twelfth row electrode coupled to the eleventh row electrode. 17.The apparatus of claim 16, the sensor layer comprising: a thirteenthsensor in the first column and the fourth physical row, the thirteenthsensor comprising: a thirteenth column electrode coupled to the firstcolumn electrode, the ninth column electrode, and the fifth columnelectrode; and a thirteenth row electrode; a fourteenth sensor in thesecond column and the fourth physical row, the fourteenth sensorcomprising: a fourteenth column electrode coupled to the second columnelectrode, the tenth column electrode, and the sixth column electrode;and a fourteenth row electrode coupled to the thirteenth row electrode;a fifteenth sensor in the third column and the third physical row, thefifteenth sensor comprising: a fifteenth column electrode coupled to thethird column electrode, the eleventh column electrode, and the thirdcolumn electrode; and a fifteenth row electrode; and a sixteenth sensorin the fourth column and the third physical row, the sixteenth sensorcomprising: a sixteenth column electrode coupled to the fourth columnelectrode, the twelfth column electrode, and the fourth columnelectrode; and a sixteenth row electrode coupled to the fifteenth rowelectrode.
 18. The apparatus of claim 17, wherein the control circuit isconfigured to: assign the ninth row electrode, the tenth row electrode,the eleventh row electrode, and the twelfth row electrode in a thirdlogical row; and assign the thirteenth row electrode, the fourteenth rowelectrode, the fifteenth row electrode, and the sixteenth row electrodein a fourth logical row, wherein the third logical row is different thanthe fourth logical row.
 19. The apparatus of claim 17, wherein the firstsensor, the second sensor, the third sensor, the fourth sensor, thefifth sensor, the sixth sensor, the seventh sensor, the eighth sensor,the ninth sensor, the tenth sensor, the eleventh sensor, the twelfthsensor, the thirteenth sensor, the fourteenth sensor, the fifteenthsensor, and the sixteenth sensor are stair-stepped diamonds.
 20. Theapparatus of claim 14, further comprising: a touch panel controllercomprising a control circuit; and interconnect coupling the touch panelto the touch panel controller; and wherein the control circuit isconfigured to assign the first row electrode, the second row electrode,the third row electrode, and the fourth row electrode in a first logicalrow.